Echolocating whales and bats express the motor protein prestin in the inner ear: a potential marker for hearing loss

Prestin is an integral membrane motor protein located in outer hair cells of the mammalian cochlea. It is responsible for electromotility and required for cochlear amplification. Although prestin works in a cycle-by-cycle mode up to frequencies of at least 79 kHz, it is not known whether or not prestin is required for the extreme high frequencies used by echolocating species. Cetaceans are known to possess a prestin coding gene. However, the expression and distribution pattern of the protein in the cetacean cochlea has not been determined, and the contribution of prestin to echolocation has not yet been resolved. Here we report the expression of the protein prestin in five species of echolocating whales and two species of echolocating bats. Positive labelling in the basolateral membrane of outer hair cells, using three anti-prestin antibodies, was found all along the cochlear spiral in echolocating species. These findings provide morphological evidence that prestin can have a role in cochlear amplification in the basolateral membrane up to 120-180 kHz. In addition, labelling of the cochlea with a combination of anti-prestin, anti-neurofilament, anti-myosin VI and/or phalloidin and DAPI will be useful for detecting potential recent cases of noise-induced hearing loss in stranded cetaceans. This study improves our understanding of the mechanisms involved in sound transduction in echolocating mammals, as well as describing an optimized methodology for detecting cases of hearing loss in stranded marine mammals

What are the toxicological effects of mercury in Arctic biota?

This review critically evaluates the available mercury (Hg) data in Arctic marine biota and the Inuit population against toxicity threshold values. In particular marine top predators exhibit concentrations of mercury in their tissues and organs that are believed to exceed thresholds for biological effects. Species whose concentrations exceed threshold values include the polar bears (Ursus maritimus), beluga whale (Delphinapterus leucas), pilot whale (Globicephala melas), hooded seal (Cystophora cristata), a few seabird species, and landlocked Arctic char (Salvelinus alpinus). Toothed whales appear to be one of the most vulnerable groups, with high concentrations of mercury recorded in brain tissue with associated signs of neurochemical effects. Evidence of increasing concentrations in mercury in some biota in Arctic Canada and Greenland is therefore a concern with respect to ecosystem health

Contributions and perspectives of Indigenous Peoples to the study of mercury in the Arctic

Arctic Indigenous Peoples are among the most exposed humans when it comes to foodborne mercury (Hg). In response, Hg monitoring and research have been on-going in the circumpolar Arctic since about 1991; this work has been mainly possible through the involvement of Arctic Indigenous Peoples. The present overview was initially conducted in the context of a broader assessment of Hg research organized by the Arctic Monitoring and Assessment Programme. This article provides examples of Indigenous Peoples' contributions to Hg monitoring and research in the Arctic, and discusses approaches that could be used, and improved upon, when carrying out future activities. Over 40 mercury projects conducted with/by Indigenous Peoples are identified for different circumpolar regions including the U.S., Canada, Greenland, Sweden, Finland, and Russia as well as instances where Indigenous Knowledge contributed to the understanding of Hg contamination in the Arctic. Perspectives and visions of future Hg research as well as recommendations are presented. The establishment of collaborative processes and partnership/co-production approaches with scientists and Indigenous Peoples, using good communication practices and transparency in research activities, are key to the success of research and monitoring activities in the Arctic. Sustainable funding for community-driven monitoring and research programs in Arctic countries would be beneficial and assist in developing more research/ monitoring capacity and would promote a more holistic approach to understanding Hg in the Arctic. These activities should be well connected to circumpolar/international initiatives to ensure broader availability of the information and uptake in policy development

Biomarkers of the cholinergic and dopaminergic signaling pathways in Arctic beluga whales (Delphinapterus leucas): Relationship to methylmercury and selenium

There are increasing concerns about potential neurotoxicity of chronic methylmercury (MeHg) exposure in Arctic wildlife and human populations. The relationships between mercury (Hg), MeHg, inorganic Hg (iHg) and selenium (Se) exposure, and neurochemical and molecular biomarkers in beluga whales (Delphinapterus leucas Pallas, 1776) were characterized. Samples were collected in 2008 (n = 20) and 2010 (n = 15) in the Canadian Arctic from hunter-harvested beluga whales. Total Hg concentrations in the temporal cortex and cerebellum were 21.0 Âą 22.6 mg kg-1 dry weight (dw) and 14.9 Âą 18.9 mg kg-1 dw, respectively. Monoamine oxidase (MAO) activity was predicted by MeHg and the molar ratio of total Hg to Se (Hg:Se, pThe accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Characterizing the development and dissemination of dietary messaging in the Inuvialuit Settlement Region, Northwest Territories

Public health communication about diet in Inuit communities must balance the benefits and risks associated with both country and store-bought food choices and processes to support Inuit well-being. An understanding of how dietary messages—public health communication addressing the health and safety of country and store-bought food—are developed and disseminated in the Arctic is currently lacking. As part of the Country Foods for Good Health study, this participatory research sought to characterize dietary messaging in the Inuvialuit Settlement Region (ISR), Northwest Territories (NWT), from the perspective of territorial, regional and local dietary message disseminators to further improve message communication in the region.   We conducted an in-person interview (n=1) (February 2020), telephone interviews (n=13) (May-June 2020), and follow-up telephone interviews (n=5) (June 2021) with key informants about their involvement in developing and/or disseminating dietary messages about the health benefits and risks of country foods and/or store-bought foods in/for the ISR. Key informants interviewed included health professionals (n=5), government employees (n=6) and community nutrition or food program coordinators (n=3) located in Inuvik, Tuktoyaktuk, Paulatuk and Yellowknife, NWT. We conducted a thematic analysis on the 19 interviews. Our findings indicate that publicly disseminated dietary messages in the ISR are developed at all scales and communicated through a variety of methods. Dietary messages focus predominantly on encouraging healthy store-bought food choices and conveying nutritional advice about store-bought and country foods. As federal and territorial messaging is seldom tailored to the ISR, representation of the Inuvialuit food system and consideration of local food realities is generally lacking. There is a need to evaluate dietary messages and improve collaborations among Inuvialuit country food knowledge holders, researchers, and public health dietary message disseminators at all scales to develop more locally tailored and culturally relevant messaging in the ISR. We recommend utilizing a participatory, collaborative, culture-centered approach to dietary message development and dissemination in northern Indigenous contexts

Informing the Co-Development of Culture-Centered Dietary Messaging in the Inuvialuit Settlement Region, Northwest Territories

Northern Indigenous communities require collaborative approaches to health communication about food that are grounded in Indigenous knowledges and cultures; however, preferences and best methods for this process remain understudied. This participatory study discusses how Inuvialuit (Inuit from the Western Arctic) knowledge and the perspectives of territorial, regional, and local dietary message stakeholders can inform the co-development of culture-centered dietary messaging to support healthy, safe, and culturally appropriate diets in Tuktoyaktuk, NWT. A community researcher in Tuktoyaktuk conducted storytelling interviews with country food knowledge holders (n = 7) and community members (n = 3), and a talking circle with local public health dietary message disseminators (n = 2) in June–July 2021. The lead author conducted key informant telephone and videoconference interviews with territorial and regional dietary message disseminators (n = 5) in June 2021. Interviews were coded and analyzed thematically. Our findings indicate that participants at all levels support increased inclusion of cultural and community perspectives about food to develop regionally and locally tailored dietary messaging. While most dietary message stakeholders wish to be involved in co-development processes, some country food knowledge holders in Tuktoyaktuk expressed a desire to lead local communications about country foods. Informed by participants’ experiences and needs, we provide recommendations for future community-led approaches to further (co-)develop and communicate effective, culturally meaningful dietary messaging that promotes Inuvialuit food sovereignty

Inuvialuit Traditional Ecological Knowledge of Beluga Whale (Delphinapterus leucas) Under Changing Climatic Conditions in Tuktoyaktuk, NT

This paper documents Inuvialuit TEK of beluga, including ecology and behaviour, hunting techniques, and food preparation under changing climatic conditions in Tuktoyaktuk, NT. Beluga Whale (Delphinapterus leucas) are an important food source for Inuvialuit in the western Canadian Arctic, a region that is experiencing dramatic climate change. Data were collected using semi-directed interviews with 17 Inuvialuit beluga harvesters and participant observation. The research found that Inuvialuit beluga harvesters possess detailed rational knowledge of beluga, particularly regarding hunting techniques and food preparation, both which are guided by a moral code about how to behave with respect to beluga. In terms of beluga ecology and behavior, Inuvialuit knowledge is limited to anecdotal reasoning drawing on generalized observations of beluga and the accounts of others. Inuvialuit are experiencing the effects of climate change, but seem to be coping thus far in the context of beluga harvesting but ongoing change in the region may increase risks associated with hunting and preparing beluga in the future.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

"That's how we know they're healthy": The inclusion of Traditional Ecological Knowledge in beluga health monitoring in the Inuvialuit Settlement Region.

Beluga from the Eastern Beaufort Sea (EBS) population are harvested annually in the Inuvialuit Settlement Region (ISR) during their seasonal migration past coastal communities and harvest camps. The beluga harvest monitoring program is a flagship program of the ISR’s Fish and Marine Mammal Community Monitoring Program (FMMCMP) and has provided critical information about beluga health and observed changes in the EBS population. This study aimed to develop a suite of local indicators of beluga health that bridged Traditional Ecological Knowledge (TEK) about beluga condition, illness and disease, with western science through the co-production of knowledge. Community members from Inuvik, Paulatuk and Tuktoyaktuk with beluga harvesting and preparation experience were engaged to characterize beluga health from an Inuvialuit perspective. Inuvialuit knowledge about the environment and beluga health, values about hunting beluga, and Inuvialuit cosmology – the foundation of the knowledge system – were documented through semi-structured questionnaires (n = 66), semi-structured interviews (n = 78) and focus group meetings (n = 3). This research furthers our understanding of how Inuvialuit view beluga health from the physical and behavioural characteristics of belugas, values and appropriate behaviours by harvesters and how observations made about beluga can be explained. To support the co-production of knowledge, a suite of local indicators was developed that bridged TEK about beluga condition, illness and disease with western science.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Description of Cochlear Morphology and Hair Cell Variation in the Beluga Whale

Environmental change and decreased ice cover in the Arctic make new areas accessible to humans and animals. It is important to understand how these changes impact marine mammals, such as beluga whales (Delphinapterus leucas Pallas, 1776). Hearing is crucial in the daily lives of cetaceans. Consequently, we need normal baselines to further understand how anthropogenic noise affects these animals. Relatively little is known about the inner ear morphology of belugas, particularly the organ of Corti, or hearing organ, found within the cochlea. The base of the cochlea encodes for high frequency sounds, while low frequencies are detected in the apex. We showed differences between the apex, or centremost point of the cochlea, and the base, the region closest to the stapes. Our results showed that average outer hair cell density changed from 148 cells/mm in the apex to 117 cells/mm in the base. Cell width varied between the two regions, from 5.8 Âľm in the apex to 8.4 Âľm in the base. These results revealed variation throughout the cochlea, and thus the need to understand the basic morphology, to give further insight on hearing function in belugas, and allow us to recognize damage if or when we find it.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Molecular and Neurochemical Biomarkers in Arctic Beluga Whales (<i>Delphinapterus leucas</i>) Were Correlated to Brain Mercury and Selenium Concentrations.

Mercury (Hg) concentrations have increased in western Arctic beluga whales (<i>Delphinapterus leucas</i>) since the industrial revolution. Methylmercruy (MeHg) is a known neurotoxicant, yet little is known about the risk of exposure for beluga whales. Selenium (Se) has been linked to demethylation of MeHg in cetaceans, but its role in attenuating Hg toxicity in beluga whales is poorly understood. The objective of this study is to explore relationships between Hg and Se concentrations and neurochemical biomarkers in different brain regions of beluga whales in order to assess potential neurotoxicological risk of Hg exposure in this population. Brain tissue was sampled from hunter-harvested beluga whales from the western Canadian Arctic in 2008 and 2010. Neurochemical and molecular biomarkers were measured with radioligand binding assays and quantitative PCR, respectively. Total Hg (Hg_T) concentration ranged from 2.6–113 mg kg^–1 dw in temporal cortex. Gamma-amminobutyric acid type A receptor (GABA_A-R) binding in the cerebellum was negatively associated with Hg_T, MeHg and total Se (Se_T) concentrations (<i>p</i> ≤ 0.05). The expression of mRNA for GABA_A-R subunit α2 was negatively associated with Hg_T and MeHg (<i>p</i> ≤ 0.05). Furthermore, GABA_A-R binding was positively correlated to mRNA expression for GABA_A-R α2 subunit, and negatively correlated to the expression of mRNA for GABA_A-R α4 subunit (<i>p</i> ≤ 0.05). The expression of <i>N</i>-methyl-d-aspartate receptor (NMDA-R) subunit 2b mRNA expression was negatively associated with iHg_labile concentration in the cerebellum (<i>p</i> ≤ 0.05). Variation of molecular and/or biochemical components of the GABAergic and glutamatergic signaling pathways were associated with MeHg exposure in beluga whales. Our results show that MeHg exposure is associated with neurochemical variation in the cerebellum of beluga whales and Se may partially protect from MeHg-associated neurotoxicity